Lock-stitch sewing-machine



H A. L. BARRY.

LOCK STITCH SEWING MACHINE.

APPLICATION FILED DEC. n, 1920.

Patentgd J fine 7 1921.

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LOCK STITCH SEWING MACHINE.

APPLICATION FILED 050.11. 1920.

Patented J 1 116 7, 1921.

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HERBERT ALFRED LUCAS BARRY, OF LONDON, ENG-LAND, AEfSIGNOR TO SILVER LOCK -S'1ITGH SEWING MACHINE SYNDICATE LIMITED, F BLOOIVISBURY, LONDON, ENG- LAND, A BRITISH LIMITED LIABILITY COMPANY.

LOCK-STITCH SEWING-MAGHINE.

eec ed Specification of Letters Patent.

Patented June "5, 1%21.

Application filed Deccmber 11, 1920. Serial no. 430,007.

T 0 all whom 2'25 may concern Be it known that I, HERBERT Anrnno LU- oas BARRY, a subject or the King of Great Britain and Ireland residing at 4th St. Marys Mansions, Qaddington, London, England, have invented new and useful improvements in and Relating to Lock-Stitch blewing h lachines, of which the following is a specification.

This invention relates to improvements in look stitch sewing machines and has for its object. the provision of means whereby high etiiciencv, low prime cost, lightweight, simplicity 01 construction and small upkeep and repair charges are obtained.

The invention consists in the arrangement and association of particular mechanism adapted to produce lock stitch sewing upon operation.

In order that the invention may be the.

better understood 1 will now proceed to describe the same in relation to the accompanying drawings, reference being had to the figures and numerals marked thereon. Like numerals refer to like parts in the various figures in which Figure 1 illustrates a side elevation of a machine constructed in accordance with the invention.

Fig. 2 is an end elevation of the machine illustrated in Fig. 1.

Fig. 3 is a plan view of the machine illustrated in Fig. 1. the upper projecting arm and the work table being removed to exhibit the parts normally concealed thereby.

Fig. t is a detail of the presser toot lever.

Fig. 5 is a side elevation of the detail illustrated in Fig. l.

Fig. 6 is detail of the needle thread release. I

In the drawings the mainframe 1 of the machine is formed with an arm 2, a box 3 for the needle bar actuating gear, a box 4; for the driving gear and a bed plate 5. A fly wheel 6, adapted to be rotated in known manner drives a spur wheel 7 through the intermediation of a spring pressed coupling pin 8. The spur wheel 7 engages two pinions 9 and 10; the pinion 9, through the shaft 11, disk 12, pin 13, and cam slotdevice 1 1, operating the needle bar 15, and thread feed 16, while the pinion 10 through the shaft 17, eccentric 18 and lever 19 moves the shuttle carriage 20 and operates the feed 21.

The lever 19, operated by the shaft 17, has two plane contact surfaces 22 disposed parallel to one another and mounted on one end thereof, the shuttle carriage 29 being mounted on the opposite end.

The eccentric 18 has a spherical surface which is disposed between the parallel plane contact surfaces :22 of the lever 19. said cccentric 18 oscillating the said lever 19 about its pivot 49 when rotated. The pivot is mounted in a boss 50 which is formed integral with the base plate 5 or is attached thereto in well known manner. The shuttle carriage 20 disposed on the end of the lever 19 carries the shuttle 23 ofknown construc tion and moves in an arc of a circle the center of which is coincicent with the center of movement of the lever 19. This are or movement is so disposed relative to the operative axis of the needle bar 15 that upon operation in proper sequence of the needle 2 1 and shuttle 23 with their attendant threads, stitches ha ing lock'stitch characteristics are produced.

To enable the material being sewn to be automatically fed to the needle 2% a prcsser foot 25 operating under control of the spring 26 is provided in proximity to the. needle 24 and causes the material being sewn -to be engaged by the teeth .21 of the feed 21 inknown manner. he feed 31 is operated by two cams 27 and 28 which are mounted on the shaft 17 the cam 27 being adapted to hit the feed member 21 into contact with the presser toot 25 and engage the material with the teeth 21 while the can 28 is adapted to move the feed member 21 forward while in the raised position and allow it to move backward under the tension of the spring 29 while in the lowered position.

To vary the length of stitch, the backward travel of the feed member 21 is more or less limited as desired by means of the stop 30 having a finger knob 31.

The tension on the needle thread is adjusted by means of a finger knob 10 which is adapted to vary the stress in the spring 41 and consequently the effective friction between the spring operated plates 87 and 88 between Which the thread passes on its Way from the reel 39 to the feed 16.

in association with the plates 37 and 38 is a plate 42 having a tail piece as adapted to be engaged by a cam i lformed in the linger lever as. Y

The lever L5 is pivoted at l6 and has a cam like projection e7 adapted to enthe radially extending member 48 mounted on the rod 49' or the presser foot 25. When the finger lever 15 is raised from the position illustrated in 2 the part i8 is engaged b the projection i? and raiseth thereby releasing the pressure of the foot '25 on the teeth 2i of the feed mem- 1 er 2i and simultaneously the end of the tail piece l3 is engaged by the cam which releases the needle thread.

The tension on the shuttle thread is adjusted in known manner and calls for no specific explanation.

In prozrhnity to the fly Wheel (3 a spool winding device is disposed, the friction wheel thereof being adapted to be moved into engagement with the pei'ip cry of the fly Wheel 6. To enable this to be readily etlected the device is pivoted at B l, a clamping screw being provided so that the pe phery 0:? the friction wheel may be main ained in contact with the periphery oi the fly Wheel 6 for spool Winding and out of contact when normal operation oi the machine is required.

During the spool Winding operation the spring pressed coupling pin 8 transmitting motion from the fly Wheel 6 to the spur Wheel 7 is disengaged thereby obviating shuttle carriage 20.

It will be seen that by the construction outlinedthe Work table 51 has no moving parts mounted thereon or attached thereto thus enabling the machine to'be readily as sembled and timed Without the Work table 51 being in position.

When not in use a cover may be our ployed to protect the machine from dirt and damage, said cover being maintained in position by means 01' suitable latches which may engage projections such as 36. To enable the size of the cover to be reduced to a minimum the handle (3 of the fly wheel 6 may be removed when the cover is to be employed.

1 claim In a sewing machine having a head carrying a presser foot bar and a lever for lifting the same, a thread tension comprising a stud projection from said head, a pair of tension disks loosely mounted on the stud a spring on said stud forcing one of said disks toward the other, a plate on said stud interposed between the outer disk and the spring and having a tail piece extending from one edge of the plate at right angles thereto to project into the path oi the lever, and a cam surface on said lever engage-able with the tail piece to move the plate against the action of the spring and thereby release the pressure on the plates.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

HERBERT ALFRED LUCAS BARRY. l Vitnesses CHARLES J. R. BULLOUGH, OLIVE VEST. 

